This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-274379, filed Sep. 28, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a catheter such as a balloon catheter, or an intravascular therapeutic or diagnostic catheter.
In accordance with the development of the microcatheter, it becomes possible to perform microvascular or intravascular therapy and diagnosis, which has been considered impossible with conventional catheters. Examples of the microcatheter are catheters for percutaneous transluminal coronary angioplasty, used for cardiac infarction or angia pertoris (referred to as a balloon catheter hereinafter). In the operation of angioplasty, it is necessary to exchange one catheter for another many times. The catheter must be exchanged, for example, when the balloon size is changed or a diagnostic or treatment device for diagnosing or treating a vicinity of a stenosed portion is changed. As an example of the method of exchanging a catheter, there is a conventionally known technique in which a long exchange guide wire is used. However, it requires not only a long period of time to handle such a long wire, but also at least two operators for the operation, and therefore the handling of the wire is not easy. In order to solve this drawback, a so-called xe2x80x9crapid exchangexe2x80x9d type catheter has been proposed. The catheter of this type has a structure in which only the distal portion thereof tracks the guide wire.
Examples of the catheter of the rapid-exchange type are discussed in U.S. Pat. Nos. 5,040,548, 5,061,273 (to Yock), U.S. Pat. No. 4,762,129 (to Bonzel), U.S. Pat. No. 5,135,535 (to Kramer) and the like.
Here, the rapid-exchange type catheter disclosed in PCT Publication WO93/15786 will now be described in detail. This catheter consists of a proximal shaft, a distal shaft, a balloon and a tube for guide wire lumen, and a core wire which extends in the direction of the distal shaft, is bonded to the proximal shaft. The core wire imparts rigidity to the distal shaft having a relatively low rigidity, which is attached to the distal side of the proximal shaft having a relatively high rigidity. In this manner, kinking in the distal shaft due to heavy concentration of flexural stress, can be prevented.
However, in this catheter, the core wire is present inside the inflation lumen, which narrows the cross sectional area of the inflation lumen. This causes the problem of inhibiting of shortening the balloon inflation/deflating time. As a result, the time for stemming the blood flow during the inflation of the balloon is prolonged, putting stress on a patient. Not only the rapid-exchange type catheter has such a drawback, but it is also common to all the catheters of the type in which a core wire is installed in a flow path as a reinforcing member.
In the meantime, PCT Publication WO92/03178 discloses a rapid-exchange catheter having such a structure that an intermediate sleeve section is provided between a proximal shaft made of a metal tube and a distal shaft having high flexibility, and a coil member is provided around the outer circumference of the sleeve section for reinforcement.
However, even if a coil member is provided around the outer circumference of the intermediate sleeve section, it is not possible to effectively avoid kinking caused by heavy concentration of flexural stress. The coil member is would in only one direction toward the distal end of the catheter, and therefore as the operator rotates the catheter in an opposite direction while gripping the hub, the wound coil is loosened and accordingly gaps between adjacent coil wires are widened, thereby causing deterioration of the kink resistance. Moreover, because the intermediate sleeve section is superfluously bent due to the loosening of the coil, there may be caused a problem that torque or pushing force, which is provided on the proximal end of the catheter, is hard to be surely transmitted to the distal end of the catheter.
The object of the present invention is to provide a catheter capable of effectively avoiding kink caused by heavy concentration of flexural stress, without narrowing cross sectional area of the inflation lumen.
A balloon catheter of the present invention includes: a tubular proximal shaft having a relatively high rigidity; a tubular distal shaft having rigidity lower than that of the proximal shaft; a tubular intermediate section disposed between the proximal shaft and the distal shaft; a hub arranged near a proximal end of the proximal shaft, to which a pressure applying device is attached; a balloon provided to a distal portion of the distal shaft to be in fluid communication, to which pressure is applied from the hub; and a guide wire lumen having a distal aperture located on a distal end side of the distal end of the balloon and a proximal aperture located on a further proximal end side of the proximal end of the balloon, through which a guide wire is inserted; wherein a reinforcing member consisting of a braided member formed by braiding at least one linear member, is embedded in the intermediate section.
A catheter of the present invention includes: a proximal shaft having relatively high rigidity; a distal shaft having rigidity lower than that of the proximal shaft; an intermediate section disposed between the proximal shaft and the distal shaft; a hub arranged near a proximal end of the proximal shaft; a treatment device (device for therapy or diagnose, such as an ultrasonic diagnostic device, a laser, an atherectomy cutter, a medicine supply device, a radio frequency generator or an ultrasonic therapy device) attached on a distal portion of the distal shaft; and a guide wire lumen having a distal aperture located on a distal end side of the treatment device and a proximal aperture located on a proximal end side of the proximal end of the treatment device, through which a guide wire is inserted; wherein a reinforcing member consisting of a braided member formed by braiding at least one linear member, is embedded in the intermediate section.
In the present invention, it is preferable that the distal shaft having relatively high rigidity should be made of a metal tube. Further, the present invention may be of a structure in which the intermediate section has an inner layer and an outer layer, and the reinforcing member is embedded between the inner surface and outer surface of the intermediate section, or of a structure in which the reinforcing member is embedded in the intermediate section such that it is exposed to an internal lumen of the intermediate section.
It is preferable in the present invention that the reinforcing member should be made by braiding linear member(s) such that there are sections where the inclination angles of the linear member(s) which constituting the reinforcing member are relatively large and relatively small with respect to the axial direction of the intermediate section.
According to the catheter of the present invention, the cross section of the inflation lumen is not narrowed and therefore the balloon inflation/deflation time is not prolonged, unlike in the prior art where the core wire is used. Therefore, it becomes possible to reduce the stress on a patient. Further, the reinforcing member which is made of a braided member exhibits a greater effect of preventing kink, than in the case of a reinforcing member made of a conventional coil member. Furthermore, when the reinforcing member is made by braiding at least one linear member such that there are sections where the inclination angles of the linear member(s) constituting the reinforcement member are relatively large and relatively small with respect to the axial direction of the intermediate section, it becomes possible to vary the rigidity of the shaft gradually. Consequently, the kink can be more efficiently avoided.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.